diff --git a/chrono/timespan.cpp b/chrono/timespan.cpp
index 5c3ff72..c0843c2 100644
--- a/chrono/timespan.cpp
+++ b/chrono/timespan.cpp
@@ -11,7 +11,6 @@
 #include <cstdlib>
 #include <iomanip>
 #include <sstream>
-#include <vector>
 
 using namespace std;